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OBJECTIVES: The aim was to investigate how workers interpret and act upon results from self-assessment of exposure (SAE). METHODS: Workers in four sawmills in Sweden were supplied with diffusive samplers for measurement of terpenes. Workers received both oral and written instructions about terpenes, their medical effects and how to handle the samplers. Responsibility for sampling was left to the individual worker; written feedback about terpene levels was provided after each measurement. The number of measurements was registered. The workers and supervisors were interviewed about their attitudes, perceived control of their work environment, need for preventive actions and future surveillance of the workplace. RESULTS: In total, 28 workers performed 100 terpene measurements. At one sawmill, there was a significant association between exposure levels and the number of measurements performed by each worker (rho = 0.79, P = 0.03). Contrary to instructions, supervisors played an important role in spontaneous organization of the measurements at each mill. Four measurements revealed terpene concentrations that exceeded the occupational exposure limits, and one preventive action was taken as a consequence of high levels. Seventy percent of the workers could not identify any reason for more measurements. Only 15% considered the measurements as their 'own' project, and the rest stated that they participated in order to satisfy the researchers. CONCLUSIONS: Previous studies have shown that workers can perform valid measurements, both select a day and technically perform measurements. This study indicates that this ability is not sufficient to ensure that measurements will be done or that implementing measurements will result in preventive actions. Workers need additional support to take preventive actions and use SAE for ongoing surveillance.

The objective of this study was to examine workers’ mental interpretation models developed in response to occupational chemical exposure. The study was performed in six companies within the reinforced plastics industry in northern Sweden, in which styrene was used; 32 workers participated in the study. Each worker performed between four and seven exposure measurements. Before receiving each result of the second to seventh measurements, the workers were asked to predict the level of their next exposure measurement. Their predictions were evaluated with respect to two judgmental principles: coherence (that the predictions are based on logical decision rules, that is, the mean value of the prior exposure levels); and correspondence (the predictions have high empirical accuracy) by calculating the mean absolute percent forcast error (MAPE). The coherence principle was tested by comparing each of the workers’ predictions with the mean, median, and last exposure level (last value) of the prior measurements. The correspondence principle was tested by comparing the worker’s prediction with the outcome of the measurement. The coherence principle was found to be the best descriptor of the workers’ predictions and the median model had the best fit. The mean model had a similar but significantly poorer fit (MAPE values of 29 and 31, respectively). The correspondence model had a poor fit with a MAPE of 54. The workers’ predictions were generally lower than their average exposures. We conclude that the workers’ interpretation model can be best described by a coherence model rather than by a correspondence model.

The aim of this study was to describe experts' decision processes leading to measurements of occupational chemical exposure. Safety engineers, clinical occupational hygienists, and work environment inspectors (four from each group) were interviewed according to a semistructured scheme. We analyzed: (i) perceived triggers for measurements, (ii) the experts' decision criteria for performing measurements when there was a trigger, and (iii) sampling strategy. Regarding triggers, all safety engineers reported a “request” from, for example, an employer; all work environment inspectors reported “legal demands;” and all clinical occupational hygienists reported “symptoms among workers.” As a decision criterion, all the interviewees reported that they measured only if they expected sufficiently high levels. The results of the present study highlight factors that trigger measurements and are of importance in determining whether measurements will be performed. These factors appear to be related to the expert's professional role and may bias the assessment of exposure. Thus, when using data from routine measurements done by experts, the possibility of a bias needs to be considered.